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iannovic
Level 2
October 5, 2017
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Investigating the cause of open sessions and bad site performance!

  • October 5, 2017
  • 13 replies
  • 4888 views

Hi everyone,

My AEM Production instance is experiencing very high garbage collection CPU Usage and performance issues. I think it might be because of sessions being left open.

I am checking /system/console/jmx on one of the publishers experiencing high garbage collection (over 60% cpu usage over 10+ hours)

I know that by default, there is ~85 SessionStatistics mbeans, and right now there is ~119 SessionStatistics mbeans. I think that very large objects on the heap are being retained due to these sessions staying open. These large objects are related to Search or QueryBuilder (based on a heap dump I checked)

The sessions that are staying open and their start times are directly related to the spikes in garbage collection.

org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-434675@Oct 4, 2017 2:39:22 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-435491@Oct 4, 2017 2:40:34 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-442302@Oct 4, 2017 2:49:22 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-443169@Oct 4, 2017 2:50:34 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-467825@Oct 4, 2017 3:35:40 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-468804@Oct 4, 2017 3:38:06 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-471911@Oct 4, 2017 3:45:39 PM"
org.apache.jackrabbit.oakSessionStatistics"repository-reader-service@session-472840@Oct 4, 2017 3:47:59 PM"

These are the sessions being started that seem to spike my  GC CPU usage.

There is about 3 other sessions that are associated with each of these repository-reader-services that are staying open, Two from admin@session, and one from anonymous@session.

Is there anywhere i can find out more information about repository-reader-services sessions being started? What should my next steps be in solving this problem?

Any advice is GREATLY appreciated!

Thank you!

Ian

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    Best answer by joerghoh

    Hi,

    The JCR queries need memory to perform the query. But when search takes a long time, and more and more queries come in, then the memory usage increase with each query.

    If you gc.log doesn't show any increase in garbage collection and you don't get OutOfMemory exceptions, there is no issue with memory at all. Rather focus on improving the searches to speed them up.

    Jörg

    13 replies

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    joerghoh
    Adobe Employee
    joerghohAdobe EmployeeAccepted solution
    Adobe Employee
    October 6, 2017

    Hi,

    The JCR queries need memory to perform the query. But when search takes a long time, and more and more queries come in, then the memory usage increase with each query.

    If you gc.log doesn't show any increase in garbage collection and you don't get OutOfMemory exceptions, there is no issue with memory at all. Rather focus on improving the searches to speed them up.

    Jörg

    I
    iannovicAuthor
    Level 2
    October 6, 2017

    Ok I will focus on search speed then,

    Thank you for your insight and time

    jimt82977416
    jimt82977416
    July 17, 2019

    Universal GC Log analyser, GCeasy's advanced machine learning algorithm saves time and hassle from dealing with cryptic CG logs. You can quickly detect memory leaks, long GC pauses, premature object promotions plus many other performance impacting problems. Powerful to tune your application's memory and GC settings. Key performance Indicators and GC statistics section of the report, helps you to tune to perfection.

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